This is a single center open label study designed to establish a tolerable dose of Antibody C225 administered over a range of dose levels during conventional irradiation in previously untreated patients with head and neck cancer that is not resectable for curative intent. Patients will be recruited from the population of cancer center patients and referrals from other institutions. The primary study evaluation parameter is safety - signs and symptoms of C225 toxicity when given in combination with radiotherapy. Tumor response evaluation by physical examination will be conducted weekly. Tumor response evaluation by radiographic film will be conducted after the completion of the therapy. The maximum tolerated dose is defined as the dose preceding the highest dose level at which 3 2 patients experience any C225 related grade 3 or grade 4 toxicity.